Gunmen in Mexico have killed another top Mexican police official – just one day after the head of the national anti-narcotics effort was shot dead. Esteban Robles headed the anti-kidnapping unit of the Mexico City police department. He was shot several times outside his home on Friday. Mr Robles was flown to a nearby hospital, but died shortly afterwards. The news came as Mexico’s president was attending a memorial service honouring three other senior police officers.